This invention relates to solenoid operated fuel injectors, which are used to control the injection of fuel into an internal combustion engine.
The dynamic operating characteristics of fuel injectors, i.e., movement of a closure member within a fuel injector, are believed to be set by several factors. One of these factors is believed to be calibrating the biasing force of a resilient element acting on the closure member, i.e., tending to bias the closure member to its closed position.
It is believed that a known fuel injector uses a spring to provide the biasing force. In particular, it is believed that a first end of the spring engages an armature fixed to the closure member and a second end of the spring engages a tube that is dedicated solely to the dynamic calibration of the spring. It is believed that the spring is compressed by displacing the tube relative to the armature so as to at least partially set the dynamic calibration of the fuel injector. It is believed that the tube is subsequently staked into its position relative to the armature in order to maintain the desired calibration.
It is also believed that filtering the fluid passing through fuel injectors can minimize or even prevent contaminants from interfering with a seal between the closure member and a valve seat. It is believed that a known fuel injector includes a filter that is generally proximate to a fuel inlet of the fuel injector.
It is believed that a disadvantage of these known fuel injectors is that separate elements are used for the calibrating and the fuel filter, and these elements are handled in independent manufacturing processes. Typically, it is believed that the known fuel injectors are first dynamically calibrated using a first element, and then a separate filter element is subsequently added. The multiplicity of elements and manufacturing steps is costly, both in terms of money and time.
It is believed that there is a need to reduce the cost of manufacturing a fuel injector by eliminating the number of components and combining assembly operations.
The present invention provides a fuel injector for controlling fuel flow to an internal combustion engine. The fuel injector comprises a body, a seat, an armature assembly, a resilient member, and a member. The body extends along a longitudinal axis. The seat is secured to the body and defines an opening through which fuel flows. The armature assembly moves along the longitudinal axis with respect to the body between first and second positions. The first position is spaced from the seat such that fuel flow through the opening is permitted, and the second position contiguously engages the seat such that fuel flow is prevented. The resilient member biases the armature assembly toward the second position. And the member extends parallel to the longitudinal axis between a first portion and a second portion. The first portion supports the resilient member and engages the body, and the second portion has a filter.
The present invention further provides a method of setting dynamic calibration for a fuel injector. The fuel injector has a body extending along a longitudinal axis, a seat secured to the body, an armature assembly moving along the longitudinal axis with respect to the seat, and a resilient member biasing the armature assembly toward the seat. The method comprises providing a member extending between a first portion and a second portion, fixing a filter to the second portion, moving the member along the longitudinal axis with respect to the body; and engaging the first portion with respect to the body such that the first portion supports the resilient member in a predetermined dynamic state.